Laboratory Considerations for Reporting Cycle Threshold Value in COVID-19

Rivak Punchoo; Sachin Bhoora; Avania Bangalee

Laboratory Considerations for Reporting Cycle Threshold Value in COVID-19

EJIFCC. 2022 Aug 8;33(2):80-93. eCollection 2022 Aug.

Authors

Rivak Punchoo^{1

2}, Sachin Bhoora², Avania Bangalee^{1

3}

Affiliations

¹ Tshwane Academic Division, National Health Laboratory Services, Pretoria, South Africa.
² Department of Chemical Pathology, Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa.
³ Department of Medical Virology, Faculty of Health Sciences, University of Pretoria, Pretoria, South Africa.

PMID: 36313906
PMCID: PMC9562486

Abstract

The Coronavirus Disease 2019 (COVID-19) pandemic is caused by the SARS-CoV-2 RNA virus. Nucleic acid amplification testing (NAAT) is the mainstay to confirm infection. A large number of reverse transcriptase polymerase chain reaction (RT-PCR) assays are currently available for qualitatively assessing SARS-CoV-2 infection. Although these assays show variation in cycle threshold values (Ct), advocacy for reporting Ct values (in addition to the qualitative result) is tabled to guide patient clinical management decisions. This article provides critical commentary on qualitative RT-PCR laboratory and clinical considerations for Ct value reporting. Factors contributing to Ct variation are discussed by considering relevant viral life-cycle factors, patient factors and the laboratory total testing processes that contribute to the Ct variation and mitigate against the reporting of Ct values by qualitative NAAT.

Keywords: COVID-19; Ct value; RT-PCR; SARS-CoV-2; cycle threshold; quantifiable cycle.

Publication types

Review